Slide rheostat having linearity adjustment



April 9, 1968 KAZU SUZUKI 3,377,603

SLIDE RHEOSTAT HAVING LINEARITY ADJUSTMENT Filed June 24, 1966 INVENTOR.

KAZU SUZUKI a-cgmsxk ATTORNEY United States Patent Office 3,377,603 SLIDE RHEOSTAT HAVING LINEARITY ADJUSTMENT Kazu Suzuki, Tokyo, Japan, assignor to Yokogawa-Hewlett-Packard, Ltd., Tokyo, Japan, a corporation of Japan Filed June 24, 1966, Ser. No. 560,332 4 Claims. (CL 338-121) ABSTRACT OF THE DISCLOSURE The modes of application of this invention are described below with reference to the drawing in which FIGURE 1 is a perspective view of a round slide rheostat embodying this invention, FIGURE 2 is a side sectional view,

FIGURE 3 is the sectional view along line AA of FIGURE 1, and FIGURES 4 and 5 are rear and partial sectional views, respectively, of conventional rheostats. A conventional rheostat is shown in FIGURES 4 and 5 in which a resistance element 14 is disposed substantially concentrically about and normal to the rotary shaft 1 on which a movable contactor 4 is fixed, The movable contactor slides along the upper edge of the resistance element, as shown in FIGURE 5, and the resistance element 14 may be selectively displaced from its regular concentric position by the radially-disposed adjusting screws 17 placed at selected intervals around the circumference of the rheostat. However, for adjusting the deviation from the linearity of output resistance value in relation to the rotational position of the shaft, the radially-disposed adjusting screws around the entire periphery must be approached from the side of rheostat thus making it very difficult to adjust linearity in an instrument where many parts are compactly crowded around the periphery of the rheostat. However, in the present invention, such adjustment can be easily carried out from the back of the instrument by turning adjusting screws which are facing toward the base plate 7 parallel to the rotary shaft in a rheostat of much simpler contruction.

In the drawing, rotary shaft 1 is centered at the center hole 11 of base plate 7 (or the panel to which the rheostat is fixed, not shown in the figure) in a way that rotation is possible. In ring plate 5, its plate surface is nearly parallel to fixed base plate 7 and crosses rotary shaft almost in a right angle, its rim is aligned concentrically with rotary shaft 1, and consequently linear resistor 6 approximately coincides with the circle centered at shaft 1. Contactor rod 4 is fixed to brush arm 2 via the brush plate made of a spring material and is in constant contact with linear resistor 6 and slides along the outer rim of linear resistor 6 as rotary shaft 1 is turned. Contactor rod 4 is fixed on brush plate 3 in such a way, as shown in FIGURE 2, that it bears an adequate angle to the directional line Y which crosses the sliding line of linear resistor 6 when ring plate is fixed to base plate 7 in the normal condition (i.e., where ring plate 5 is regarded as substantially flat). Ring plate 5 is a thin plate made of an elastic material which can be flexed in the direction of Y, and as shown in FIGURE 2. Ring plate 5 has a number of penetrating holes 12 bored at selected intervals with an adjusting screw 8 having a recessed part 13 clamped for free rotation within each of the penetrating holes 12. These adjusting screws 8 screw into the 3,3 77,603 Patented Apr. 9, 1 968 base plate 7 such that by controlling the tightness of adjusting screws 8, ring plate 5 (along with resistor 6) is partly flexed, as shown in FIGURE 2; in the direction of Y. Consequently, when brush arm 2 (and therefore contactor rod 4) is in a selected position, the contact point between contactor 4 and resistor 6 can be changed and the resistance value between one end of the resistor (10', for example) and contact point may be controlled Simply by adjusting screws 8.

Thus, the linearity of the resistance element 6 which has a resistance value between one end andany point that varies according to the length along the: element, can be easily compensated to. eliminate deviations from the desired linearityduei to such non-linearizing factors as variations in resistance value per unit length and eccentricity of resistance element 6 with respect to shaft 1.

In the example described above, the flexible ring plate 5 is a thin. plate flexible in Y direction (up and down in the figure) with a fine line. resistance element 6 fixed to the outer rim of ring plate 5 along a portion of the circumference thereof. Ring plate 5 may either be an insulator or metal provided, in the latter case, that resistance element 6 is electrically insulated from the ring plate 5. It should be understood, however, that the resistance element of the rheostat may be in the form of a resistive flexible ring plate or, over an insulating flexible ring plate, a thin film of resistive material may be coated in the shape of a ring with contact to be made along the outer rim. Also, the flexible ring plate may have a spiral rim provided that the contactor is also made movable along the spiral rim. In general, the structure should have a contact rim which is flexible in a direction which is approximately parallel to the rotatable central shaft 1 that moves contactor 4 along the rim. In this description,

such structures are referred to as flexible plate resistor structures.

The linear resistor element 6 of FIGURE 1 must be fixed along the circular rim of the flexible ring plate 5. Consequently the linear resistor element 6 should also be a freely deformable material such as a fine core of a synthetic fiber (e.g. polyvinylchloride) around which is wound a layer of fine resistance wire.

I claim:

1. Electromechanical apparatus comprising:

a signal conductive element having flexibility in one direction and being disposed along a selected path normal to the direction of flexibility;

a movable electrical connection member mechanically supported with respect to said signal conductive element to move along said path for electrically connecting to said element at points along the length thereof and having an elongated contact surface which is slanted with respect to said direction of flexibility; and

means coupled to said element for positioning said element in the direction of flexibility at a selected location along said path relative to the positions of said element at other locations along said path, the positioning of said element at said selected location altering the point along the length of the signal conductive element connected to said electrical connection member at a selected position thereof adjacent said selected location along said path in response to positioning of said element in the direction of flexibility.

2. Electromechanical apparatus as in claim 1 wherein:

said signal conductive element is a resistive element disposed along an edge of a support plate which is flexible in a direction substantially normal to the surface plane thereof; and

4. Electromechanical apparatus as in claim 3 cornprising:

a plurality of adjustment screws disposed at selected angular positions around said support plate near the periphery thereof, each of said adjustment screws being disposed to alter the position of the peripheral edge of said support plate near said screw in said said electrical connection member is disposed within a plane defined by an axis from the edge of the support plane substantially normal to the surface plane thereof and by an axis in the direction along said path and is slanted relative to said axes for altering the location along said resistive element at which connection to the connection member is made in response to the flexing in said direction of said support plate and resistive element attached thereto for a direction of flexibility relative to the positions of the I h l selected position of said connectlon member along 10 f f g iz ggi ii is Suppolt plate near other of said path. 3. Electromechanical apparatus as in claim 2 wherein: said support plate is substantially circular and said References Cited resistive element is attached thereto along the outer UNITED TATES PATENTS periphery; 15 3,075,062 1/1963 Iaccarino 200-67.7 X sald electrical connectlon member is mechanically sup- 3,305,650 2/1967 Dumem et 2O0 67 7 ported on a shaft located centrally of said support plate for rotation about an axis substantially normal to the surface plane thereof and is disposed to contact said resistive element along the length thereof 20 ROBERT S M ACON Examiner and is slanted relative to the surface of the support plate within a plane which is normal to a radius from the axis of rotation of said shaft. I

ROBERT K. SCHAEFER, Primary Examiner.

H. J. HOHAUSER, Assistant Examiner. 

